The present invention relates to a cyclonic vacuum cleaner.
Cyclonic vacuum cleaners typically have a dirty air inlet, a clean air outlet, an airflow path between the inlet and outlet, and dirt and dust separating apparatus arranged in the airflow path between the dirty air inlet and the clean air outlet. The dirt and dust separating apparatus comprises a centrifugal separator having a cylindrical or tapering chamber with a tangential inlet at a first end and a dirt and dust collecting portion at a second end opposite the first end. In use, dirty air is drawn into the cleaner by means of a fan and motor unit through the dirty air inlet. The dirty air is passed to the centrifugal separator where it enters the cylindrical or tapering chamber via the tangential inlet. The dirt and dust is separated from the airflow within the chamber and collected in the dirt and dust collecting portion thereof whilst the clean air exits the cleaner via the clean air outlet.
The term xe2x80x9ccyclonic vacuum cleanerxe2x80x9d is applicable to any type of vacuum cleaner, including upright, cylinder or canister, backpack, industrial and robotic cleaners. Many types of cyclonic vacuum cleaner are know. Examples of cyclonic upright cleaners are shown and described in, inter alia, EP 0 042 723, EP 0 037 674, EP 0 636 338, U.S. Pat. No. 4,593,429 and US Re 32 257. A cyclonic backpack cleaner is disclosed in U.S. Pat. No. 5,267,371 and a cylinder cyclonic cleaner is disclosed in EP 0 778 745.
Generally in known cyclonic vacuum cleaners, the cyclone arrangement is such that, in normal modes of operation, the cyclone is orientated so that the longitudinal axis thereof is either vertical or inclined at an acute angle to the vertical. This is to allow the effects of gravity to assist the collection of the dirt and dust separated from the airflow. The collected dirt and dust drops to the end of the bin remote from the inlet and is collected there. In some arrangements, the cyclonic separator includes two (or more) cyclones. However, in all cases, both or all of the cyclones are arranged so that the axes of the cyclones are, in the normal mode of operation, vertical or inclined at an acute angle to the vertical so that the effects of gravity can be put to good use in assisting the separation and collection of the separated dirt and dust.
There are instances when the vertical height of a vacuum cleaner is preferably kept to a minimum, for example when the vacuum cleaner is required to be used underneath articles of furniture or in other area, where there is a height restriction. Vacuum cleaners of the type already known can be used for short periods in a mode which brings the cyclonic separator into or near to a horizontal position (i.e. with the axis of the cyclone lying horizontally), but the effects of gravity are then lost and the orientation of the cyclone and its collecting chamber or bin can result in reduced separation efficiency of the cyclone. It is therefore generally understood that a cyclone which is orientated with its axis lying horizontally is not as efficient at separating dirt and dust from an airflow as one which has its axis arranged vertically, or at most inclined at an acute angle to the vertical. Our copending International patent application WO 00/36968 describes a cyclonic vacuum cleaner where the cyclonic separator is mounted with its longitudinal axis lying in a substantially horizontal position. This minimises the vertical height of the cleaner. We have found that, under certain conditions, it is possible for dust to be re-entrained into the airstream during use or for dust to fall out of the inlet when emptying such a cleaner.
The present invention seeks to provide an improved cyclonic vacuum cleaner of the kind which can operate in a substantially horizontal position.
An aspect of the invention provides a vacuum cleaner comprising a cyclonic separation unit, the unit comprising a chamber having a dirty air inlet and a cleaned air outlet at a first end thereof and a dirt collection portion at a second end thereof, which unit, in use, cleans dirty air entering the inlet by centrifugal separation and stores the dirt in the dirt collection portion, the cyclonic separation unit being supported on the cleaner such that the inlet is located in a lower portion of the first end of the chamber and such that, in normal use, the longitudinal axis of the chamber lies in, or can be brought to lie in, a substantially horizontal position, and wherein a shield member is provided at the inlet for shielding the inlet from the dirt collection portion of the chamber.
This helps to provide a cyclonic vacuum cleaner which is compact in the vertical direction, and therefore which is capable of cleaning within confined areas having height restrictions, while the shield member minimises the problems of re-entrainment of dust during horizontal operation or loss of dust while removing the separation unit from the cleaner.
One application of the cleaner is in the field of robotic vacuum cleaners, i.e. cleaners which carry navigation equipment and sensors which will allow the vacuum cleaner to navigate itself around a room or other area to be cleaned without human intervention. In such an application, the vacuum cleaner includes supporting wheels, drive means for driving the wheels, sensors for sensing objects in the path of the cleaner and control means for avoiding contact with any such objects. However, the invention is applicable to vacuum cleaners which are not robotic in nature.
Preferably the circumferential length of the shield member is at least as great as the circumferential length of the inlet so that the shield fully covers the inlet.
The shield can take the form of a fin which extends radially inwards from an outer wall of the chamber. Advantageously, the separation unit has a helical entry guide extending from one side of the inlet and the shield extends parallel to the entry guide on the other side of the inlet. The shield member can be an extension of the helical entry guide, forming the beginning of a second revolution around the chamber.
Preferably, the shield extends inwardly from an outer wall of the chamber to meet an insert which fits inside the chamber adjacent the inlet. Indeed, the shield can be formed integrally with the insert. The insert can be a shroud.
Preferably, the inlet is oriented in a substantially vertical direction and the shield extends vertically alongside the inlet.
Preferably, the separation unit is mounted above the cleaning head of the cleaner and is directly coupled to an output of the cleaner head. The shield has been found to offer a flow-straightening effect which permits the inlet to the separation unit to be positioned more closely to the cleaning head.
Preferably the inlet to the separation unit is a tangential inlet through the side of the chamber.